A method for predicting the secondary porosity system (SPS) porosity, and thereby permeability; of a coal bed involves determining an initial condition in the coal bed, including an initial SPS pressure and an initial sorbed gas composition, determining a pressure strain effect due to increasing the...http://www.google.co.uk/patents/US20040060351?utm_source=gb-gplus-sharePatent US20040060351 - Process for predicting porosity and permeability of a coal bed
